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Question about Megaprims


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i just found out recently that i can make Megaprims by myself. Did they change the prim size limit? Or do i have special powers? I have noticed other people still can't make Megaprims, but some others can.

But i remember alot of sim owners didn't like the use of Mega prims because they said they would cause lag. Well do they still dislike Prims that are bigger than 10x10m? Or is it ok to use them now?

I mean... to me they seem to be "legal" and even the Megaprims from those Prim packs are resizable now :)


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(FYI - I am one of the people who made megaprim sets for builders before the capability was generally available.)

Since the introduction of the Mesh-capable viewers, LL has allowed prim creation and re-sizing up to 64 Meters. Increasing the prim size limit was necessary for mesh to be useful. So now, the newer viewers can resize any prim to as much as 64 M in any dimension, and the server code allows it. This includes the former megaprims.

Prior to the release of mesh, a server-side code clamped the max size any prim could be resized to at 10 M, and clamped the max size a prim could be created as also at 10M. Megaprims were created when the server code accidentally omitted one of those limits - the limit on initial prim creation size - and individuals used the glitch to make big prims.

The "issues" with prims larger than 10 M in size were largely due to two factors:

1)The original Havok 1 physics simulation engine that was in use in the SL Simulator code at the time when Megaprims were first introduced handled large prims very badly. This was especially true if they were made physical, but also affected things badly even if they were not physical when avatars or other prims were colliding with them. A megaprim dance floor loaded with avatars could raise hell with sim physics calculations. This problem has largely been eliminated by newer server code releases that have newer versions of Havok.

2) The first Megaprims, made by a resident named Gene Replacement, were available in a very limited range of sizes. There were really only a dozen or so that Gene made. But people rapidly found they could use "prim torture" - IE path cut, slice, dimple, hollow, and other alterations - to reduce the apparent size of the prims and make other handy shapes. For example, cutting a 100 x 100 x 100 cube to make what appeared to be a 50 x 50 x 1 plane. Soon over 200 Megaprim sizes were floating around the grid, and the majority relied on prim torture to make them that size.

The major problem there is that the bounding box for the prim remained the same, and any interactions that happened "within" that megaprim's bounding box could get strange, because the simulators just were not made to cope with things like an avatar moving around inside a prim, or rezzing a prim against the cut surface of another prim. This is actually an issue with any size prim, but being huge magnifies the problems. If you cut and twist a prim to make a jagged rock surface, you can't walk normally right on the apparent surface. You end up hovering above it.

Think for a moment about using that cut down 100 M cube as a 50 x 50 x 1 wall at the edge of a small parcel of land. Depending on how you place it and how you shaped it to make that apparent shape, the bounding box could extend as much as 99 Meters past your parcel's edge, and an extra 50 M above the top of the wall, encroaching on other people's land and making things work strangely for them. The prim's center could actually be 49 Meters past the edge of your land, on someone else's parcel and using their prim count, even though what you see appears to be entirely on your parcel.

What has changed:

Several years ago, another server code glitch made it possible, for about 3 or 4 days, to make new Megaprims. A dozen or so people, including myself, made large assortments of megaprims in a variety of actually useful sizes, intended to be used as-is, to make, for example, a 100 M long straight stretch of road, or a 100 M long picket fence.

Because those prims didn't need to be "tortured" to be a useful size, they were much less disruptive to the simulators and to your neighbors. The bounding boxes were exactly what you expected from what you could see. The new physics code handled them just fine. The same is true of the up to 64 M prims that you are allowed to make today. If used reasonably and responsibly, prims up to 64 M in size are fine now. LL could have set that limit higher, but they chose to go with 64 M as the new maximum to cut back on parcel encroachment issues.

There are still some issues with megaprims.

There's a ton of places in the server and viewer code that still assume 10 M is the normal max prim size. The mini-map, for example, can't display megaprims correctly at all. 

Megaprims can still be used to encroach on other parcels to grief someone. 

Megaprims, if made physical, can still be created in quantity to cause major problems in a sim.

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  • 6 months later...

Hello all,


I was able to create mega prims just like everyone else with the update then suddenly lost my ability.

I have a builder alt that I use to hold certain items and that account has lost the ability as well.

I have loaded different viewers, looked though the system options, and asked many but every solution given does not seem to work.

Please if you know of a way to reset my viewer, accounts or whatever please let me know...

Thank you so much : ]


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